Lessons learned from contamination with endotoxin originated from the supplement in the cell culture medium

• Published in: Regenerative therapy 2024-12, Vol.27, p.230-233
• Main Authors: Uehara, Koaki, Oshiro, Eriko, Ochiai, Atsushi, Takagi, Ryo, Yamato, Masayuki, Kato, Atsunaga
• Format: Article
• Language: English
• Subjects: Cell-based medicinal products; Certificate of analysis; Cholera toxin; Endotoxin; Stratified epithelial cell
• ISSN: 2352-3204; 2352-3204
• DOI: 10.1016/j.reth.2024.03.022

Endotoxin is a typical pyrogen derived from the outer membrane of Gram-negative bacteria. In fabricating cell-based medicinal products, it is necessary to control endotoxin in the process and the products. In the quality control tests of our clinical study, endotoxin concentration in the culture supernatant of autologous oral mucosal epithelial cell sheets exceeded the criterion value. Therefore, endotoxin measurements were conducted to clarify the cause of the endotoxin contamination. The reagents used to prepare the culture medium, the unused culture medium, and the culture supernatants were diluted with pure water. Endotoxin concentrations in the diluted samples were measured. Endotoxin was detected in both the unused culture medium and the culture supernatant of the epithelial cell sheets at higher concentrations than the criterion value. Therefore, endotoxin concentrations in the reagents used to prepare the culture medium were measured and were found to be below the criterion value, except for cholera toxin. On the other hand, three lots of cholera toxin products were used for the measurement, and the endotoxin concentrations were higher than the criterion value. The results indicate that the endotoxin contamination is caused by the cholera toxin product. To prevent endotoxin contamination in cell-based medicinal products, endotoxin concentrations in reagents used for the fabrication should be measured in the facility conducting clinical research or confirmed by an adequate certificate of analysis from the manufacturers of the reagents. •Our clinical study was interrupted by endotoxin contamination.•The cause of the contamination in the cell-based medicinal product was identified.•The endotoxin originated from the culture medium supplied with the cholera toxin.•Cholera toxin products disclosing the amount of endotoxin are available.•A certificate of analysis should be provided by the material manufacturers.